Fluctuation in spore numbers of aquatic hyphomycetes in the Nihotupu Stream, Waitakere Ranges, was examined using a filtration technique. Low spore numbers were recorded in spring and summer, with higher numbers in autumn and winter. No significant differences were found in the patterns for different fungal species. The fluctuation in spore numbers in the stream corresponded closely to those for northern hemisphere streams with low pH and mixed conifer‐broadleaf vegetatio